Content uploaded by Hamid Reza Roosta
Author content
All content in this area was uploaded by Hamid Reza Roosta on Mar 04, 2019
Content may be subject to copyright.
Journal Identification = HORTI Article Identification = 3941 Date: May 20, 2011 Time: 2:35 pm
Scientia Horticulturae 129 (2011) 396–402
Contents lists available at ScienceDirect
Scientia Horticulturae
journal homepage: www.elsevier.com/locate/scihorti
Effects of foliar application of some macro- and micro-nutrients on tomato plants
in aquaponic and hydroponic systems
Hamid R. Roostaa,∗, Mohsen Hamidpourb
aDept. of Horticultural Sciences, Faculty of Agriculture, Vali-e-Asr University of Rafsanjan, Rafsanjan, Iran
bDept. of Soil Science, Faculty of Agriculture, Vali-e-Asr University of Rafsanjan, Rafsanjan, Iran
article info
Article history:
Received 4 August 2010
Received in revised form 5 April 2011
Accepted 6 April 2011
Keywords:
Aquaculture
Aquaponic
Foliar application
Hydroponic
Tomato
abstract
An aquaponic system was designed to investigate effects of foliar applications of some micro- and macro-
nutrients on tomato growth and yield in comparison with a hydroponic system. Common carp, grass carp
and silver carp were stocked in the rearing tanks at 15, 20 and 15 fish m−3, respectively. The fish were
fed three times daily with a pellet diet containing 46% protein. Fourteen days old tomatoes seedlings
were transplanted on to growth bed units of aquaponic and hydroponic systems after stocking of carp
fish for 2.5 months in the rearing tanks. Foliar nutrients application began 30 days after transplan-
tation. Eight treatments were used, untreated control, foliar application at the rate of 250 mL plant−1
with 0.5 g L−1K2SO4, MgSO4·7H2O, Fe-EDDHA, MnSO4·H2O, H3BO3, ZnCl2, and CuSO4·5H2O. Plants were
sprayed twice a month. The results showed that biomass gains of tomatoes were higher in hydroponics
as compared to aquaponics. Foliar application of K, Mg, Fe, Mn, and B increased vegetative growth of
plants in the aquaponics. In the hydroponics, only Fe and B had positive effects on plant growth. Cluster
number per plant in aquaponics was lower than in hydroponics treatments, but it increased with foliar
application of elements. There was no difference in fruit number and yield between aquaponics and
hydroponics grown plants in the control treatments. Except Cu, foliar spray of all elements significantly
increased plant fruit number and yield in the aquaponics in order of: K > Fe > Mn > Zn >Mg>B. In the
hydroponics, foliar application of K, Mg and Zn increased fruit number and yield of plants compared to
control. These results indicated that foliar application of some elements can effectively alleviate nutrient
deficiencies in tomatoes grown on aquaponics.
© 2011 Elsevier B.V. All rights reserved.
1. Introduction
Aquaponic is the integration of hydroponic plant production
into recirculating fish aquaculture systems (Nelson, 2008). In the
aquaponic system, nutrients which are excreted directly by the
fish or generated by the microbial breakdown of organic wastes
are absorbed by plants cultured hydroponically. Aquaponics has
several advantages over other recirculating aquaculture systems
and hydroponic systems that use inorganic nutrient solutions. The
hydroponic component serves as a biofilter, and therefore a sep-
arate biofilter is not needed as in other recirculating systems.
Aquaponic systems have the only biofilter that generates income,
which is obtained from the sale of hydroponic produce such as
vegetables, herbs and flowers (Rakocy and Hargreaves, 1993). Fish
feed provides most of the nutrients required for plant growth.
Majority of fish species utilize 20–30% of nitrogen (N) supplied
by the diet (Penczak et al., 1982; Hall et al., 1992; Shpigel et al.,
∗Corresponding author. Tel.: +98 3913202031; fax: +98 3913202042.
E-mail address: roosta h@yahoo.com (H.R. Roosta).
1993; Piedrahita, 2003; Schneider et al., 2005). This means that
about 70–80% of the N supplied by the feed are being released as
waste into the water (Krom et al., 1995). Ammonia is the major
end product in the breakdown of proteins in fish. Fish digest the
protein in their feed and excrete ammonia through their gills and
in their feces. Ammonia also enters the system from bacterial
decomposition of organic matter such as uneaten feed or dead
algae.
The most common recirculating aquaponic systems employ
either a media filled raised bed, nutrient film technique (NFT), or
floating raft system (Anonymous, 1997; Diver, 2006; Lennard and
Leonard, 2006; McMurtry et al., 1997; Rakocy et al., 2006, 1997;
Watten and Busch, 1984) for the plant growing area. Among them,
the floating raft system was selected for tomato production in this
experiment.
It is reported that aquaponic systems that rely solely on fish
waste to supply nutrients for plants have low levels of phospho-
rus (P), potassium (K), iron (Fe), manganese (Mn) and sulfur (S)
(Adler et al., 1996; Seawright et al., 1998; Graber and Junge, 2009).
Thus, optimizing plant production may require fertilizer supple-
mentation in aquaponic systems (Rakocy et al., 1997). On the other
0304-4238/$ – see front matter © 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.scienta.2011.04.006
Journal Identification = HORTI Article Identification = 3941 Date: May 20, 2011 Time: 2:35 pm
H.R. Roosta, M. Hamidpour / Scientia Horticulturae 129 (2011) 396–402 397
hand, the management of a tomato crop is somewhat more dif-
ficult than leafy crops because the nutrient demands of the plant
change during different stages of plant growth. From germination
through the development of the first flowers (about 6 weeks), the
needs of the plant are fairly constant. Once the plant starts set-
ting fruit, it requires more Ca, Mg and K (Nelson, 2008). At this
time the nutrients can be applied to the growing medium or as
a foliar spraying, which is recognized by some of the researchers
as a very efficient method of plant nutrition during the intensive
growth stage (Chauduni and De, 1975; Giskin et al., 1984; Komosa,
1990). Foliar applications of Mg, Zn, and Mn can effectively allevi-
ate deficiencies in fruit and vegetable crops grown on calcareous
soils with a pH of 7.4–8.4 (Li, 2001).
Little information is available about effects of foliar application
of nutrients on tomato yields and growth in aquaponic systems.
The objectives of this research were: (i) to investigate effects of
foliar applications of some micro- and macro-nutrients on tomato
growth and yield (ii) to compare plants growth in aquaponic and
hydroponic systems.
2. Materials and methods
2.1. Aquaponic system
An aquaponic system was designed based on the Rakocy/UVI
model (Rakocy et al., 1997) in the Vali-e-Asr University of Rafsan-
jan, Iran (Fig. 1). Our aquaponic system consisted of 3 individual,
identical aquaponic units. Each aquaponic unit consisted of one fish
rearing tanks, a clarifier, a filter tank, a degassing tank and a plant
growth bed unit. The tap water, which was located near the rearing
tanks, supplied water from a short distance to the fish rearing tank.
A water pump continuously delivered water from the fish-rearing
tanks to the rest of unit. Water from plant growth bed unit was
returned to the rearing tank, which was located in the lowest point
of the system. A plastic meshes covered the tank to prevent fish
jumping from the tank.
Each of plant growth bed unit and fish-rearing tank had 10 air
diffusers (2 L min−1), which were cleaned monthly. There were also
three air diffusers in the degassing tank. Settleable solids were
removed from the clarifiers one time daily by opening a ball valve.
Fine solids were collected by netting plastic screens in the filter
tanks and were removed two times monthly by draining the tank
and washing the netting. There was also a plastic screen at the
entrance of degassing tank which prevented fish fry to reach to
the hydroponic tank.
The pH value of water was not adjusted during the experiment;
it was in the range of 7.0–7.7. Water loss through evaporation, tran-
spiration and sludge removal was replenished with tap water in the
rearing tank and a valve in the rearing tank was used to control the
water flow so as to produce a constant water level in the rearing
tank.
The aquaponic unit operated continuously with a known density
of fish biomass to maintain stable bacterial populations. Common
carp (Cyprinus carpio), grass carp (Ctenopharyngodon idella) and
silver carp (Hypophthalmichthys molitrix) were stocked in the rear-
ing tanks (diameter 1.2 m, water depth 0.75 m, and water volume
848 L) at 15, 20 and 15 fish m−3, respectively and cultured for 6
months. The mean mass of fishes stocked ranged from 160 to 180 g.
The fish were always fed three times daily with a pellet diet contain-
ing 46% protein at a mean rate of 3% of body weight per day (Table 1).
The fish were fed and defecated entirely within the fish tank. Water
from the fish tank was continuously (24 h day−1) pumped to the
system via the water pump, thus biological filtration of the cul-
ture water was constant. Tanks were harvested after 6 months. The
fishes were weighed and counted.
Table 1
Proximate composition (%) of the fish feed used in the experiment.
Composition % FW
Protein 46
Fat 13
Ash 13
Fiber 2.5
Phosphorous 1.5
Moisture 11
2.2. Plant
Tomato seedlings were grown in pots containing perlite as a
medium for 14 days. After that, pots were transferred to the growth
bed components of aquaponic and hydroponic systems. Plants
grown in hydroponic systems were nourished with a nutrient solu-
tion consisted of: 2.5 mM Ca(NO3)2·4H2O, 0.2 mM KH2PO4, 0.2 mM
K2SO4, 0.3 mM MgSO4·7H2O, 0.1 mM NaCl, 20 M Fe-EDDHA, 7 M
MnSO4·H2O, 0.7 M ZnCl2, 0.8 mM CuSO4·5H2O, 2 MH
3BO3,
and 0.8 MNa
2MoO4·2H2O. Solutions were changed completely
every week in the first couple of weeks and subsequently every
4th day in hydroponic system. Deionized water was used for nutri-
ent solution making in hydroponic system. Tape water was used
in aquaponic system. The only nutrient supplementation in plant
growth bed unit of aquaponic systems was Fe, which was added in
a chelated form (Fe-EDDHA) at a concentration of 2 mg L−1once
every two weeks. Eight plants were growing together in each
growth bed unit of aquaponic and hydroponic systems. Foliar nutri-
ents application began 30 days after transplantation by which time
plants had attained enough leaf area for effective foliar application.
Eight treatments were used, untreated control, foliar application at
the rate of 250 mL plant−1with 0.5 g L−1K2SO4, MgSO4·7H2O, Fe-
EDDHA, MnSO4·H2O, H3BO3, ZnCl2, and CuSO4·5H2O. Plants were
sprayed twice a month. Tomato plants were trellised to overhead
wires and pruned to a single leader stem. Fruit were harvested
every week after 84–106 days after transplanting. Early yield, fruit
number, cluster number and single fruit mass were calculated from
fruits in the first three harvests.
The plants were grown in a greenhouse with 13 h light phase
(26 ±3◦C) and 11 h dark phase (22 ±3◦C). Greenhouse tempera-
ture was controlled using cool air following into greenhouse from
central cooler. The relative humidity was 52.4–63.2%.
The experiment was conducted for 108 days. At the end of the
experiments, the shoot length (SL), node number (NN) and the
leaf number (LN) were recorded. The plant organs (roots, leaves,
and stems) were harvested, weighed, oven-dried (48 h at 72◦C) for
determination of leaf fresh mass (LFM), stem fresh mass (SFM), root
fresh mass (RFM), leaf dry mass (LDM), stem dry mass (SDM) and
root dry mass (RDM).
2.3. Chemical analysis
Standard methods were used to measure pH, total alkalinity,
total dissolved solids (TDS), total ammonia-nitrogen (TAN), nitrite-
nitrogen and nitrate-nitrogen once every week at two locations in
the systems. Dissolved oxygen (DO) and water temperature were
measured periodically. Samples for water quality analysis were
collected at the influent and effluent of the growth bed tanks.
The level of chlorophyll in the youngest expanded leaves and
old leaves was recorded by taking SPAD (chlorophyll content)
readings with a SPAD-502 Chlorophyll Meter (Minolta Camera Co.
Ltd., Japan). Chlorophyll a, chlorophyll band carotenoids were
extracted from leaf tissue with methanol and estimated accord-
ing to Lichtenthaler and Wellburn (1983). Second leaves from top
(young leaves) and bottom (old leaves) were used for the measure-
ment of chlorophyll fluorescence using a Plant Efficiency Analyzer,
Journal Identification = HORTI Article Identification = 3941 Date: May 20, 2011 Time: 2:35 pm
398 H.R. Roosta, M. Hamidpour / Scientia Horticulturae 129 (2011) 396–402
Fig. 1. Schematic representation of the (a) aquaponic and (b) hydroponic systems.
Handy PEA (Hansatech Instruments Ltd., Norfolk, UK). Leaves were
maintained in darkness for 15 min before taking the data on chloro-
phyll fluorescence. Maximal quantum yield of PS II photochemistry
(Fv/Fm) were calculated using the software supplied by the manu-
facturer.
2.4. Statistical analysis
This experiment was arranged as a factorial in the framework
of a completely randomized design with two factors, growing sys-
tem (aquaponics and hydroponics) and foliar nutrient application
(K, Mg, Fe, Mn, B, Zn and Cu) with 3 replications (growth systems).
Analysis of variance (ANOVA) was performed using the SAS pro-
gram. If ANOVA determined that the effects of the treatments were
significant (p< 0.05 for F-test), then the treatment means were sep-
arated by Duncan’s multiple range test.
3. Results and discussions
3.1. Water quality
Table 2 shows some of the water quality parameters during
the experiment in the aquaponic systems. The important param-
eters in terms of fish production [nitrite (NO2−), nitrate (NO3−),
pH, EC and dissolved oxygen] were in the range of tolerance limits
(Table 2), except for nitrite which was above the 0.2 mg L−1(Graber
and Junge, 2009; Boyd, 1992; Boyd and Tucker, 1998).
3.2. Carp production
Common carp, grass carp and silver carp were stocked at 17.69,
23.58 and 17.69 fish m−3, respectively. During the harvest, produc-
tion of common carp, grass carp and silver carp averaged 8367, 9764
and 6846 g m−3, respectively. Mean harvest mass was 473, 414 and
387 g for common carp, grass carp and silver carp, respectively. It
means mean food conversion ratio for carp species was 1.43. Sur-
vival rate was 100% for all species indicating that the water quality
has been acceptable for carp growth during the experiment.
3.3. Vegetative growth
Vegetative growth of tomato in hydroponics and aquaponics
treatments is represented in Table 3. There was a significant dif-
ference (P< 0.05) between two systems in terms of biomass gain.
Although tomato leaf fresh mass (LFM), stem fresh mass (SFM),
root fresh mass (RFM), leaf dry mass (LDM), stem dry mass (STM),
leaf number (LN), node number (NN) and shoot length (SL) were
higher in hydroponics as compared to aquaponics, tomato growth
in aquaponics was normal during the experiment with no visible
signs of any severe nutrient-deficiencies. Pereira (2002) reported
that irrigation of lettuce by fish effluent increased shoot fresh mat-
ter in comparison with plants irrigated with well water. However,
when lettuce was fertilized with chemical fertilizer, no significant
difference on fresh matter was observed between plants irrigated
with fish effluent and well water. Foliar application of K, Mg, Fe,
Journal Identification = HORTI Article Identification = 3941 Date: May 20, 2011 Time: 2:35 pm
H.R. Roosta, M. Hamidpour / Scientia Horticulturae 129 (2011) 396–402 399
Table 2
Water quality during the experiment and tolerance limits for fish production in the influent and effluent of growth bed component of aquaponic system.
Parameter Influent of growth bed unit Effluent of growth bed unit Tolerance limits (Graber and Junge,
2009; Boyd, 1992; Boyd and
Tucker, 1998)
Dissolved oxygen (mg L−1) 6.10 ±0.06 6.03 ±0.06 >6
Total alkalinity (mg L−1as CaCO3) 250 ±67 249 ±62 –
Total hardness (mg L−1) 162 ±12 161.6 ±5.7 –
pH 7.70 ±0.06 7.68 ±0.18 7–8
EC (Ms/cm) 0.54 ±0.02 0.51 ±0.01 <1.2
TDS (mg L−1) 327 ±12 338 ±24 –
NaCl (%) 1.02 ±0.14 0.63 ±0.15 –
Water temperature (◦C) 25.7 ±0.82 25.7 ±0.74 –
NO3-N (mg L−1) 34.6 ±3.1 34.9 ±2.1 <150
NO2-N (mg L−1) 1.69 ±0.32 1.57 ±0.30 <0.2
NH4-N (mg L−1) 0.33 ±0.02 0.32 ±0.02 <1.0
K(mgL
−1) 26.7 ±5.2 25.9 ±3.2 –
P(mgL
−1) 7.98 ±0.59 7.50 ±0.43 –
Ca hardness (mg L−1) 34.2 ±0.23 34.2 ±0.36 –
Fe (mg L−1) 0.21 ±0.02 0.21 ±0.03 –
Zn (mg L−1) 0.37 ±0.01 0.36 ±0.02 –
Cu (mg L−1) 0.042 ±0.01 0.042 ±0.02 –
Mn, and B increased vegetative growth of plants in the aquaponics
(Table 3). As potassium is not needed by fish, it is not added to fish
feed and thus to the system in adequate amounts (Graber and Junge,
2009). Thus, due to low level of K in aquaponic system (Table 2),
foliar spray of K increased the tomato growth in aquaponics, sig-
nificantly (Table 3). This is in agreement with the results of Kaya
et al. (2001), who reported foliar application of supplementary K
increased dry matter of tomato plants in salinity stress condition.
Tisdale et al. (1985) also observed similar behavior after foliar appli-
cation of K. In the hydroponics, only Fe and B had positive effects on
plant growth (Table 3). Higher effect of foliar application of these
elements in the aquaponics may be due to lower concentration of
them in nutrient solutions. However, it should be noted that nutri-
ents are removed without replacement for one week in hydroponic
systems, while, they are produced in aquaponics by the fish excre-
tion or by the microbial breakdown of organic wastes continuously
(Nelson, 2008).
3.4. Reproductive growth
Cluster number per plant in aquaponics was lower than in
hydroponics treatments, but it increased with foliar application of
elements (Fig. 2). The highest cluster was observed in aquaponics
Fig. 2. Effects of foliar application of macro- and micro-nutrients on the cluster
number of tomato plants in aquaponic and hydroponic systems. Bars with different
letters show significant differences at P≤0.05 (Duncan).
with foliar K and Fe applications. Copper decreased cluster num-
ber in hydroponics but it had no significant effect on aquaponic
grown plants (Fig. 2). In the control treatments, there was no
difference in fruit number and fruit yield between aquaponics
and hydroponics grown plants (Figs. 3 and 4). These observa-
tions are in agreement with Graber and Junge (2009) who noted
that there was no difference in fruit yields between hydroponi-
cally and aquaponically grown tomatoes. Except Cu, foliar spray
of all elements significantly increased plants fruit number and
yield in the aquaponics in the order of: K > Fe > Mn > Zn > Mg > B.
Due to low level of K and nutrients such as Mg, Fe, Mn and Zn
in aquaponic system and subsequently in the leaves of aquaponic-
grown plants (data not shown), foliar application of these elements
increased their concentration in aquaponic-grown plants, signifi-
cantly (Fig. 5).
In the hydroponics, foliar application of K, Mg and Zn increased
fruit number and yield of plants, but B and Cu decreased them
compared to control treatments. Castro et al. (2006) found that
irrigation with fish effluent enhanced tomato fruit number and
productivity in the first three analyzed harvest periods. However,
the increase in fruit number in treatments that received fish efflu-
ent resulted in lower mean fruit weight. They found that even
with reduction on fruit mean weight, the increase in fruit num-
Fig. 3. Effects of foliar application of macro- and micro-nutrients on the fruit number
of tomato plants in aquaponic and hydroponic systems. Bars with different letters
show significant differences at P≤0.05 (Duncan).
Journal Identification = HORTI Article Identification = 3941 Date: May 20, 2011 Time: 2:35 pm
400 H.R. Roosta, M. Hamidpour / Scientia Horticulturae 129 (2011) 396–402
Table 3
Effects of foliar application of macro- and micro-nutrients on the leaf fresh mass (LFM), stem fresh mass (SFM), root fresh mass (RFM), leaf dry mass (LDM), stem dry mass (SDM), root dry mass (RDM), node number, leaf number
and height of tomato plants in aquaponic and hydroponic systems.
Planting system Mineral nutrient LFM (g plant−1) SFM (g plant−1) RFM (g plant−1) LDM (g plant−1) SDM (g plant−1) RDM (g plant−1) Node no. (node plant−1) Leaf no. (leafplant−1) Height (cm)
Aquaponic Control 273 ±18f–h†193 ±23f 234 ±33hi 55 ±3.1ef 33.5 ±1.9g 42.9 ±1.9c–e 11.3 ±1.3b–e 20.3 ±2.3cd 194 ±15d
Fe 317 ±10e–g 265 ±13de 222 ±5i 85 ±0.8cd 55.4 ±1.9bc 38.2 ±2.6d–f 12.3 ±0.3a–d 27.3 ±0.9ab 230 ±6a–d
K 515 ±40b 426 ±15a 435 ±11ab 178 ±12.0a 69.2 ±3.6a 61.2 ±1.3a 9.7 ±0.3fg 28.0 ±1.5ab 240 ±12a–c
Mn 332 ±12d–g 313 ±16b–d 274 ±16f–i 61 ±4.7d–f 50.8 ±5.1c–e 41.2 ±3.1c–f 9.3 ±0.3g 24.0 ±1.2bc 236 ±24a–c
B 385 ±40c–e 358 ±17b 303 ±8e–g 80 ±3.1cd 58.6 ±5.4bc 60.7 ±3.2a 12.7 ±0.3a–c 26.0 ±1.5a–c 230 ±13a–d
Mg 252 ±28gh 233 ±29ef 314 ±20ef 44 ±6.3f 42.5 ±2.5ef 51.4 ±0.9b 11.0 ±0.6c–g 23.7 ±2.9bc 216 ±22b–d
Zn 285 ±25f–h 246 ±17ef 244 ±20g–i 46 ±2.1f 45.1 ±0.6d–f 45.4 ±0.8b–d 12.0 ±1.0a–c 24.0 ±2.1bc 230 ±20a–d
Cu 213 ±8h 230 ±26ef 161 ±15j 53 ±1.5f 36.6 ±3.2fg 29.5 ±1.1g 13.7 ±0.7a 17.0 ±3.2d 200 ±29cd
Hydroponic Control 485 ±26b 340 ±23bc 286 ±8e–h 111 ±10.0b 56.9 ±2.5bc 29.0 ±0.3g 10.7 ±0.3d–g 30.7 ±0.7a 258 ±7a
Fe 593 ±10a 423 ±29a 481 ±12a 98 ±10.0bc 57.8 ±1.0bc 46.5 ±2.0bc 11.7 ±0.3b–e 27.7 ±1.3ab 247 ±4ab
K 508 ±19b 330 ±21b–d 370 ±15cd 114 ±8.5b 57.9 ±0.9bc 35.9 ±3.2fg 10.7 ±0.3d–g 28.7 ±2.0ab 256 ±5ab
Mn 405 ±12cd 320 ±10b–d 272 ±18f–i 67 ±4.9d–f 53.5 ±3.3b–d 35.1 ±1.8fg 12.7 ±0.3a–c 25.7 ±1.2a–c 261 ±1a
B 630 ±42a 447 ±22a 249 ±16g–i 81 ±5.8cd 71.0 ±1.9a 30.2 ±2.4g 12.0 ±0.6a–c 28.0 ±3.1ab 246 ±13ab
Mg 637 ±35a 421 ±22a 340 ±27de 171 ±19.0a 63.0 ±1.8ab 30.0 ±2.4g 13.0 ±0.6ab 29.7 ±2.2ab 258 ±1a
Zn 458 ±24bc 288 ±19c–e 407 ±17bc 78 ±7.5c–e 44.1 ±2.6ef 38.7 ±2.4g 10.0 ±0.6e–g 28.3 ±1.3ab 262 ±2a
Cu 340 ±14d–f 328 ±32b–d 262 ±23f–i 109 ±7.6b 50.0 ±1.4c–e 29.5 ±1.0g 12.3 ±0.3a–d 23.7 ±0.3bc 252 ±6ab
†Bars with different letters show significant differences at P≤0.05 (Duncan).
Fig. 4. Effects of foliar application of macro- and micro-nutrients on the yield of
tomato plants in aquaponic and hydroponic systems. Bars with different letters show
significant differences at P≤0.05 (Duncan).
ber was enough to elevate the total productivity. Prinsloo and
Schoonbee (1987) also observed an increase in tomato yield from
64.5 to 95.8 t ha−1when plants were irrigated with fish efflu-
ent in comparison with plants which were irrigated with well
water.
Graber and Junge (2009) reported that an important lack in fish
water was its low potassium concentration, which was 45 times
lower than in hydroponic. This resulted in a poorer tomato quality
in aquaponic compared with the hydroponic production system.
Potassium limitation was reflected by fruit analysis; aquaponic
tomatoes contained 22.0gKkg
−1dry matter versus 40.8gKkg
−1
dry matter in hydroponic. Therefore, high effects of foliar applica-
tion of K on cluster number, fruit number and yield of tomato in
our experiment have been due to low amount of K in fish water
(Table 2).
The pH of aquaponic solution had been alkaline (pH 7.7) in
the present study which decreases availability and uptake of Fe,
Mn,ZnandB(Bertoni et al., 1992; Roosta, 2011) and hence foliar
application of elements can meet the requirement of plants for
these elements. In field culture, foliar application of B increased
tomato shoot and root dry weight and improved fruit set and
total yields (Davis et al., 2003). Higher fruit number and yield
in foliar-treated plants in aquaponics compared to hydroponics
Fig. 5. Effects of foliar application of macro- and micro-nutrients on the fruit fresh
mass of tomato plants in aquaponic and hydroponic systems. Bars with different
letters show significant differences at P≤0.05 (Duncan).
Journal Identification = HORTI Article Identification = 3941 Date: May 20, 2011 Time: 2:35 pm
H.R. Roosta, M. Hamidpour / Scientia Horticulturae 129 (2011) 396–402 401
Table 4
Effects of foliar application of macro- and micro-nutrients on the SPAD index, Fv/Fm and pigments in the leaves of tomato plants in aquaponic and hydroponic systems.
Planting system Mineral
nutrient
SPAD (old leaves) SPAD (young leaves) Fv/Fm (old leaves) Fv/Fm (young leaves) Chl aaChl bCarotenoid
Aquaponic Control 29.45 ±1.34e 40.08 ±0.65a–d 0.683 ±0.019ab 0.710 ±0.006a 1502 ±37a–c 668 ±8c–f 168 ±2b–e
Fe 30.57 ±1.62c–e 44.33 ±1.57ab 0.713 ±0.015ab 0.750 ±0.006a 1490 ±34a–c 693 ±48c–f 173 ±8b–e
K 29.48 ±1.71e 42.67 ±1.76a–c 0.713 ±0.007ab 0.710 ±0.032a 1477 ±5a–d 655 ±23d–f 168 ±3b–e
Mn 31.47 ±0.77b–e 43.85 ±1.64ab 0.717 ±0.012ab 0.710 ±0.017a 1726 ±15a 794 ±17c 189 ±4b
B 29.78 ±0.52d–e 44.17 ±2.37ab 0.713 ±0.009ab 0.730 ±0.010a 1427 ±62b–d 662 ±30d–f 162 ±8c–e
Mg 28.27 ±1.19e 43.90 ±2.23ab 0.713 ±0.009ab 0.733 ±0.009a 1449 ±202b–d 683 ±41c–f 227 ±5a
Zn 32.43 ±0.36a–e 39.92 ±2.50a–d 0.687 ±0.024ab 0.713 ±0.015a 1224 ±110d 621 ±40ef 158 ±9c–e
Cu 33.92 ±1.41a–d 39.17 ±1.31b–e 0.657 ±0.037b 0.710 ±0.010a 1642 ±59ab 597 ±27ef 149 ±3e–g
Hydroponic Control 32.02 ±1.46a–e 34.47 ±2.51e 0.690 ±0.015ab 0.700 ±0.025a 1276 ±18cd 596 ±48ef 153 ±2d–f
Fe 35.38 ±0.85ab 44.90 ±1.42a 0.723 ±0.012a 0.750 ±0.006a 1731 ±128a 1352 ±73a 169 ±1b–e
K 35.96 ±0.63a 32.97 ±1.57f 0.707 ±0.003ab 0.713 ±0.003a 1378 ±65bd 639 ±38d–f 134 ±1fg
Mn 32.10 ±0.87a–e 35.67 ±0.67d–f 0.693 ±0.018ab 0.710 ±0.015a 1244 ±73cd 583 ±15f 150 ±4ef
B 34.07 ±1.28a–c 37.58 ±1.49c–f 0.720 ±0.020a 0.720 ±0.021a 1595 ±31ab 757 ±28cd 175 ±5b–d
Mg 33.77 ±0.39a–d 45.25 ±0.91a 0.700 ±0.021ab 0.727 ±0.023a 1607 ±46ab 918 ±75b 127 ±6g
Zn 34.18 ±1.60a–c 35.67 ±0.33d–f 0.693 ±0.018ab 0.710 ±0.031a 1559 ±36ab 579 ±9f 232 ±19a
Cu 34.55 ±1.80a–c 37.65 ±1.60c–f 0.697 ±0.019ab 0.727 ±0.009a 1563 ±13ab 724 ±22c–e 180 ±9bc
Bars with different letters show significant differences at P≤0.05 (Duncan).
aThe amount of pigments is expressed as nmol gleaf FM−1.
may be due to low but stable concentrations of essential ele-
ments in aquaponics, in which toxicity and deficiency stresses and
imbalance of elements that is common in hydroponics, would be
avoided.
3.5. SPAD value, Fv/Fm and pigments
The plants were slightly greener in aquaponics compared with
hydroponics. In the control treatments, the chlorophyll index
in young leaves, determined as SPAD readings, was higher in
aquaponics as compared to hydroponics (Table 4). Foliar spraying
of Mg or Fe increased the SPAD value of young leaves in hydropon-
ics grown plants, while SPAD value of young leaves in aquaponics
grown plants was not affected by foliar application of any elements
(Table 4). There was no difference in maximal quantum yield of PSII
photochemistry (Fv/Fm) of young and old leaves of plants among
different treatments (Table 4). The content of chlorophyll awas
higher in aquaponics than in hydroponics grown control plants,
and foliar spraying of elements did not affect it in aquaponic grown
plants (Table 4). Greener color and higher chlorophyll content of
leaves in aquaponics grown plants could be partly due to higher
but non-toxic level of ammonium absorption by tomato plants
in aquaponics (Roosta and Schjoerring, 2007; Roosta et al., 2009).
Ammonia is the main end product of the breaking down of proteins
in fish. Fish digest the protein in their feed and excrete ammo-
nia through their gills and in their feces (Durborow et al., 1997a).
Although, most of this ammonia is then converted to nitrite (NO2−)
which is also quickly converted to non-toxic nitrate (NO3−) by nat-
urally occurring bacteria under normal conditions, plants uptake
some ammonia before its conversion to NO2−and NO3−(Durborow
et al., 1997b).
Except Mn, foliar spraying of all elements increased the content
of chlorophyll ain hydroponics grown plants (Table 4). Foliar appli-
cation of Mg and Fe increased chlorophyll bcontents of plant leaves
in both hydroponic and aquaponic systems compared to the con-
trol treatments (Table 4). Foliar application of Mg also significantly
increased the content of carotenoids in aquaponics grown plants
(Table 4). This pigment was increased by Zn or Cu in hydroponic
treatments (Table 4). Magnesium is a component of the chlorophyll
molecule and 15–30% of the total Mg in plants is associated with
the chlorophyll molecule (Marschner, 1995). On the other hand,
although Fe is not a constituent of chlorophyll, it is essential for
chlorophyll biosynthesis (conversion of Mg proporphyrin to pro-
tochlorophyllide) (Marschner, 1995). Thus, the effects of these two
elements on chlorophyll bwere due to their role in chlorophyll
biosynthesis.
4. Conclusions
The study showed that biomass gains of tomatoes were higher
in hydroponics as compared to aquaponics. Foliar application of
K, Mg, Fe, Mn, and B increased vegetative growth of plants in the
aquaponics. In the hydroponics, only Fe and B had positive effects
on plant growth. Cluster number per plant in aquaponics was lower
than in hydroponics treatments, but it increased with foliar applica-
tion of elements. Except Cu, foliar spray of all elements significantly
increased plant fruit number and yield in the aquaponics in order
of: K > Fe > Mn > Zn > Mg > B. In the hydroponics, foliar application
of K, Mg and Zn increased fruit number and yield of plants, but
B and Cu decreased them compared to control treatments. Foliar
application of Mg and Fe increased chlorophyll bcontents of plant
leaves in both hydroponic and aquaponic systems compared to the
control treatments. These findings indicated that foliar application
of some elements can effectively alleviate nutrient deficiencies in
tomatoes grown on aquaponics.
Acknowledgments
I wish to thank Vali-e-Asr University of Rafsanjan Research
Council for its approval and for providing financial support for
project with code number of Agr86HS308.
References
Adler, P.R., Takeda, F., Glenn, D.M., Summerfelt, S.T., 1996. Utilizing byproducts to
enhance aquaculture sustainability. World Aquaculture 27 (2), 24–26.
Anonymous, 1997. The Freshwater Institute Natural Gas Powered Aquaponic
System—Design Manual. The Conservation Fund Freshwater Institute, Shepard-
stown, WV.
Bertoni, G.M., Pissaloux, A., Morad, P., Sayag, D.R., 1992. Bicarbonate–pH relationship
with iron chlorosis in white lupine. Journal of Plant Nutrition 15, 1509–1518.
Boyd, 1992. Water Quality in Ponds for Aquaculture. Alabama Agricultural Experi-
mental Station, Auburn University.
Boyd, Tucker, 1998. Pond Aquaculture Water Quality Management. Kluwer Aca-
demic Publishers, Boston, London.
Castro, R.S., Azevedo Borges, C.M.S., Bezerra-Neto, F., 2006. Increasing cherry tomato
yield using fish effluent as irrigation water in northeast Brazil. Scientia Horti-
culturae 110, 44–50.
Chauduni, B.B., De, R., 1975. Effect of soil and foliar application of phosphorus on
yield of tomato (Lycopersicon esculentum Mill.). Soil Science and Plant Nutrition
21, 57–62.
Davis, J.M., Sanders, D.C., Nelson, P.V., Lengnick, L., Sperry, W.J., 2003. Boron improves
growth, yield, quality, and nutrient content of tomato. Journal of American Soci-
ety of Horticultural Science 128 (3), 441–446.
Journal Identification = HORTI Article Identification = 3941 Date: May 20, 2011 Time: 2:35 pm
402 H.R. Roosta, M. Hamidpour / Scientia Horticulturae 129 (2011) 396–402
Diver, S., 2006. Aquaponics—Integration of Hydroponics and Aquaculture. Appro-
priate Technology Transfer for Rural Areas (ATTRA), Fayetteville, AR.
Durborow, R.M., Crosby, D.M., Brunson, M.W., 1997a. Ammonia in Fish Ponds. SRAC
Publication 463, pp. 1–2.
Durborow, R.M., Crosby, D.M., Brunson, M.W., 1997b. Nitrite in Fish Ponds. SRAC
Publication 462, pp. 1–4.
Giskin, M.L., Santos, A.T., Etcheves, J.D., 1984. Can the foliar application of essential
nutrients decrease fertilizer inputs? In: Proc VIIth Colloquium for the Optimal-
ization of Plant Nutrition, vol.I,Montpellier Cedex, France.
Graber, A., Junge, R., 2009. Aquaponic systems: nutrient recycling from fish wastew-
ater by vegetable production. Desalination 246, 147–156.
Hall, P.O.J., Holby, O., Kollberg, S., Samuelsson, M.O., 1992. Chemical fluxes and mass
balances in a marine fish cage farm. IV. Nitrogen. Marine Ecology Progress Series
89, 81–91.
Kaya, C., Kirnak, H., Higgs, D., 2001. Enhancement of growth and normal growth
parameters by foliar application of potassium and P in tomato cultivars grown
at high NaCl salinity. Journal of Plant Nutrition 24, 353–367.
Komosa, A., 1990. Influence of some properties of chemical solutions and nutritional
status of plant on efficiency of foliar fertilization of greenhouse tomato. Rocz.
AR Poznafi. Research dissertation, 210 pp.
Krom, M.D., Ellner, S., Van Rijn, J., Neori, A., 1995. Nitrogen and phosphorus cycling
and transformations in a prototype ‘non-polluting’ integrated mariculture sys-
tem, Eilat, Israel. Marine Ecology Progress Series 118, 25–36.
Lennard, W.B., Leonard, B.V., 2006. A comparison of three different hydroponic sub-
systems (gravel bed, floating and nutrient film technique) in an Aquaponic test
system. Aquaculture International 14, 539–550.
Li, Y., 2001. Calcareous Soils in Miami-Dade County. Fact Sheet SL 183. Soil and
Water Science Department, Florida Cooperative Extension Service, University of
Florida, Gainesville, FL, Available at http://edis.ifas.ufl.edu/TR004 (April 5, 2007).
Lichtenthaler, H.K., Wellburn, A.R., 1983. Determination of total carotenoids and
chlorophylls a and b of leaf extracts in different solvents. Biochemical Society
Transactions 603, 591.
Marschner, H., 1995. Mineral Nutrition of Higher Plants, 2nd ed. Academic Press,
Cambridge, UK.
McMurtry, M.R., Sanders, D.C., Cure, J.D., Hodson, R.G., Haning, B.C., Amand, P.C.,
1997. Efficiency of water use of an integrated fish/vegetable co-culture system.
Journal of the World Aquaculture Society 28, 420–428.
Nelson, R.L., 2008. Aquaponic Food Production. Nelson and Pade Inc. Press, Montello,
WI, USA, 218 pp.
Penczak, T., Galicka, W., Molinski, M., Kusto, E., Zalewski, M., 1982. The enrich-
ment of a mesotrophic lake by carbon, phosphorus and nitrogen from the cage
aquaculture of rainbow trout, Salmo gairdneri. Journal of Applied Ecology 19,
371–393.
Pereira, E.W.L., 2002. Utilizac¸ão de efluente de viveiro de peixes na irrigac¸ão
de alface cultivadaemdiferentes tipos de substrato.Monog. deGrad.Eng.Agron.
Escola Superior de Agricultura de Mossoró, Mossoró, RN, Brasil, 32 pp.
Piedrahita, R.H., 2003. Reducing the potential environmental impact of tank aqua-
culture effluents through intensification and recirculation. Aquaculture 226,
35–44.
Prinsloo, J.F., Schoonbee, H.J., 1987. Investigation into the feasibility of a
duck–fish–vegetable integrated agriculture–aquaculture system for developing
areas in South Africa. Water SA 13 (2), 109–118.
Rakocy, J.E., Bailey, D.S., Shultz, K.A., Cole, W.M., 1997. Evaluation of a commercial-
scale aquaponic unit for the production of tilapia and lettuce. In: Fourth
International Symposium on Tilapia in Aquaculture, vol. 1 , pp. 357–
372.
Rakocy, J.E., Losordo, T.M., Masser, M.P., 2006. Recirculating Aquaculture Tank Pro-
duction Systems: Integrating Fish and Plant Culture, vol. 454. Southern Region
Aquaculture Center Publication, pp. 1–16.
Rakocy, J.E., Hargreaves, J.A., 1993. Integration of vegetable hydroponics with
fish culture: a review. In: Wang, J.K. (Ed.), Techniques for Modern Aquacul-
ture. American Society of Agricultural Engineers, St. Joseph, MI, USA, pp. 112–
136.
Roosta, H.R., 2011. Interaction between water alkalinity and nutrient solution pH
on the vegetative growth, chlorophyll fluorescence and leaf Mg, Fe, Mn and Zn
concentrations in lettuce. Journal of Plant Nutrition 34, 717–731.
Roosta, H.R., Sajjadinia, A., Rahimi, A., Schjoerring, J.K., 2009. Responses of cucum-
ber plant to NH4+and NO3−nutrition: the relative addition rate technique
vs. cultivation at constant nitrogen concentration. Scientia Horticulturae 121,
397–403.
Roosta, H.R., Schjoerring, J.K., 2007. Effects of ammonium toxicity on nitrogen
metabolism and elemental profile of cucumber (Cucumis sativus L., cv. Styx)
plants. Journal of Plant Nutrition 30, 1933–1951.
Schneider, O., Sereti, V., Eding, E.H., Verreth, J.A.J., 2005. Analysis of nutrient
flows in integrated intensive aquaculture systems. Aquacultural Engineering
32, 379–401.
Seawright, D.E., Stickney, R.R., Walker, R.B., 1998. Nutrient dynamics in integrated
aquaculture-hydroponics systems. Aquaculture 160, 215–237.
Shpigel, M., Neori, A., Popper, D.M., Gordon, H., 1993. A proposed model for “envi-
ronmental clean” land-based culture of fish, bivalves and seaweeds. Aquaculture
117, 115–128.
Tisdale, S.L., Nelson, W.L., Beaton, J.D., 1985. Soil Fertility and Fertilizers, 4th ed.
Macmillan, New York.
Watten, B.J., Busch, R.L., 1984. Tropical production of tilapia (Sarotherodon aurea) and
tomatoes (Lycopersicon esculentum) in a smallscale recirculation water system.
Aquaculture 41, 271–283.
